The present invention relates to slide mounts for film transparencies.
A wide variety of projectors have been developed for projecting film transparencies onto projection screens or other suitably reflective surfaces. Typically, the transparencies are individually mounted in slide mounts which in turn are stored within slide racks or trays, such as the well-known carousel-type tray. The trays are mounted on the projector for sequential transportation of the slides through the projection system. The most popular projectors are designed to handle the two-inch square slide mounts used to support 35-millimeter film transparencies. Additionally, the better projectors register each projected slide against a reference surface fixed with respect to the projection lens to provide a "critical focus" registration for each slide, eliminating the need to refocus each slide individually.
Although providing adequate projection of stationary images, known 35-millimeter projectors typically do not include structure for rotating the projected image. Rotation is desirable in many applications, such as planetarium shows, to provide a realistic display of a galaxy, planet, or satellite. Although highly specialized devices and projectors have been developed for rotatably supporting conventional 35-millimeter slide mounts, these devices are not without their drawbacks. One such system includes a relatively large slide-supporting assembly for rotatably supporting a slide mount. Additionally, this system includes a relatively complicated slide transportation mechanism for rotating the slide-supporting device. This projector is relatively complicated, expensive, and prone to down time because of the delicate mechanisms and slide-supporting devices involved. Second, the large, custom-made slide-supporting devices are not interchangeable with conventional slide mounts in a slide tray and, therefore, are not usable in conventional projectors.